Population Genetics, Mating Systems, and Molecular Epidemiology

Little is known about the genetic structure in parasite populations, much less what factors shape these patterns. Genetic structure can influence evolutionary outcomes such as speciation, adaptations to host defenses, and host adaptations to parasite virulence. For parasites of medical, veterinary, or commercial importance, genetic structure has important implications for the evolution of drug resistance and epidemiological models. My research integrates ecological principals in parasitology with population genetics theory to investigate evolutionary mechanisms that affect the genetic variation within and among parasite populations. A practical application that stems from my research is the use of population genetics methods to identify foci of transmission in human parasites (i.e., molecular epidemiology). Elucidation of parasite mating systems (e.g., selfing versus outcrossing) and factors that affect inbreeding in natural populations of parasites are other topics of interest.

Biodiversity, Conservation, and Natural History

The biodiversity and natural history of parasites in many systems remain uncharacterized. This is unfortunate because parasites can constitute a significant proportion of the biomass in an ecosystem, regulate host populations, alter individual host behaviors, and be an important component in food-web chains. Furthermore, many parasites have complex life cycles that require the use of invertebrate and vertebrate hosts. Thus, the presence of a parasite indicates that the required hosts are present in the ecosystem. Such knowledge on parasite community structure can be used to asses “ecosystem health”. A future goal is to establish a biodiversity/conservation research program that incorporates helminth parasite diversity in coastal wetland research around the Gulf of Mexico.

Schistosomes infect over 200 million people across Africa and South America. The genome for the human parasite Schistosoma mansoni (blood flukes) has been sequenced. In collaboration with researchers at SFBR (Tim Anderson) and UTHSCSA (Phil LoVerde), I developed a linkage map for S. mansoni. The goal is to use linkage mapping methods (QTL mapping) to understand the genetic basis of medically and epidemiologically relevant traits such as intermediate host (snails) specificity and drug-resistance. A future goal is to us an ecological genomics approach to examine how the genes at the host-parasite interface vary in different environments and influence the distribution and abundance of the parasite and host. For the linkage map, I have developed ~300 microsatellite markers across the genome. These markers will also be useful in studying the molecular epidemiology of S. mansoni in human populations and assessing ecological correlates of genetic diversity.